(Note that up until February 2015, there was an additional targeting option called interest targeting. This option has been retired and Google advises advertisers to switch to affinity or custom affinity instead.)

In this article I’ll delve into the newest targeting type, custom affinity targeting. I’ll start by describing a common aspect of affinity, in-market, affinity and remarketing target: they all allow advertisers to display ads to groups of people who share characteristics. Ads might be shown when people in these groups visit any web site on the Google Display Network (GDN). So ads “follow people around” as they visit GDN sites.

This type of targeting can be even more effective than topic targeting because reach (the number of people who see the ad) and frequency (the average number of times an ad is viewed by one person) can be greater.

Furthermore, custom affinity audiences consist of people who share finely-grained characteristics. For example, one of the affinity audiences is “avid investors”. A business selling gold coins could create a custom affinity audience consisting of people who are avidly investing in gold coins.

Let’s walk through the process of creating such a custom audience. We’ll create the ad group “Gold Coin Investors” and create the custom audience at the same time:

We choose “Affinity Audiences,” from the “Interests & remarketing dropdown, and then see a screen like this:

We then click on the “Create custom affinity” button, which leads to this screen:

The field indicated by the red arrow is where we’ll tell Google the characteristics of the target audience, and examples of sites that the audience members might frequent.

Google has told me that this field should contain at least 10 entries – e.g. 5 keywords and 5 URLs. We’ll enter the keywords first, pressing the Tab key after each entry:

Next we’ll enter 5 URLs of sites that our target audience might frequently visit. This is where another tool comes in handy: the Display Planner, found under the Tools menu:

We’ll enter “gold coin collecting” as the seed keyword, and then click on the “Get placement ideas” button:

We’re then presented with a screen that lists a wealth of URLs that we could use in defining our custom audiences:

We’ll choose the top five and include them in our custom audience definition field:

Note the “Preview custom audience” button at the bottom of the screen shot. Clicking on this yields some important information about the audience we’ve just created:

We see that the size of the audience is 65 million to 70 million (the campaign is targeting the US and Canada), demographics of the audience, and the types of websites the audience frequents.

We’ll click on the Save button, and we’re done! Once we add text and/or image ads appealing specifically to gold coin collectors/investors, we’ll have a very powerful ad group indeed. You can expect average CTRs and average conversion rates to be higher than ad groups using less-specific targeting methods – often as high as you experience for Remarketing campaigns!